HP execs are claiming they were misled by Autonomy when former CEO Léo Apotheker made the second-largest acquisition in the company's history last year.

That alleged deception accounted for most of an $8.8 billion writedown the company's taking.

But what exactly are they accusing the former management team at Autonomy of doing?

The allegations are that people at Autonomy ran their books in such a way that it made the company seem more valuable than it was. AllThingD's Arik Hesseldahl offers a good rundown of the charges:

Of HP's $8.8 billion writedown announced today, $5 billion is related to the alleged fraud at Autonomy. The rest comes from impairment of goodwill and other intangible assets related to the acquisition, prompted by the drop in HP's stock price.

HP says Autonomy was selling some low-margin hardware at a loss but booking those sales as high-margin software sales.

It was allegedly hiding this by reporting some portion of the cost of those products as a marketing expense, rather than as a cost of goods sold.

HP is also accusing Autonomy of not properly reporting deals to license its software to resellers—partners who sold Autonomy software with packages of hardware or services. These deals were allegedly reported as revenue in advance of actual sales to customers using the software.

HP is also accusing Autonomy of not booking its software-as-a-service sales correctly. Revenue on software-as-a-service deals should only be recognized when the customer pays, according to accounting standards—typically on a monthly subscription basis. HP says Autonomy was reporting these deals as if they were software-license agreements and recognizing all the revenue upfront.

Mike Lynch, Autonomy's CEO at the time of the deal, who also ran Autonomy as an HP unit for a period after the sale, denies any wrongdoing and says that HP's examination of the company's financials before the deal was made, was "exhaustive," involving representatives from HP and outside firms KPMG, Barclays, and Perella Weinberg.